Double Check Your Gear

[victor]

One reason not to fully crank a valve open is that it can (not likely but can) result in damage to the valve when the temperature changes. Different metals expand and contract at different rates as the temperature changes. The change in temp as you dive could result in the seal being compressed against its stop with much greater force than you intended when you opened it. Given that the construction of the valve is not designed to meet an over open pressure this could result in damage.
Like I said unlikely however this was common practise and I am sure is normal in some industries where valves are common.

 

[Dr Neil]

Has anyone asked a valve manufacturer what they recommend? I dug out the paperwork from a valve less than five years old and there was nothing recommending opening the valve completely then closing it a quarter or half turn.

I think this urban legend of the "backing off" of the valve is in the same category of turning a SPG away from you when you open the cylinder valve. When was the last time a SPG exploded?

I teach students to hold their SPG in their hand while they fully open their cylinder valve. That way they can immediately check their cylinder pressure.

 

[ScoobaDood]

If you feel you need this product, you may want to reconsider scuba diving. Take up golf, and hit ball with flat side of club...

I disagree..I think these valves add another layer of protection. Personally, I like the fact that any DM should be able to see my valve is open and not mess with it.

Why is it that when people want to add a simple device to scuba diving to perhaps make it easier to avoid a dangerous mistake, the answer back from some people is "don't dive, you are too stupid" or "diving isn't for you" or in this case "you may want to reconsider scuba diving" ?

I think it is just one more layer of protection. Make sure the green ring is showing, physically check the valve, take a couple of breaths while watching your gague, and have a great dive. Hmmm no harm from that comes to mind.

As always, just my $.02

 

[captndale]

I think this urban legend of the "backing off" of the valve is in the same category of turning a SPG away from you when you open the cylinder valve. When was the last time a SPG exploded?

I have seen many instructors demonstrate turning the valve on while holding the gauge with the face turned away from them. The problem is, they were starring right into the overpressure relief plug on the back of the SPG.

 

[Steve50]

"need" a condition marked by the lack of something requisite.

just sayin...

 

[Thalassamania]

I disagree..I think these valves add another layer of protection. Personally, I like the fact that any DM should be able to see my valve is open and not mess with it. If I want something checked, I'll ask.

Any DM should know to keep his or her fingers off my valve.

Why is it that when people want to add a simple device to scuba diving to perhaps make it easier to avoid a dangerous mistake, the answer back from some people is "don't dive, you are too stupid" or "diving isn't for you" or in this case "you may want to reconsider scuba diving" ?

Because the intelligent approach to diving dictates the minimum amount of gear with the minimum complexity possible, but there are any number of manufacturers incessantly trying to flog new pieces of gear as necessities and redesigned gear the is more complex than it needs to be.

I think it is just one more layer of protection. Make sure the green ring is showing, physically check the valve, take a couple of breaths while watching your gague, and have a great dive. Hmmm no harm from that comes to mind.

I would not refuse to dive using such a valve, I just see no reason to seek one out.

Has anyone asked a valve manufacturer what they recommend? I dug out the paperwork from a valve less than five years old and there was nothing recommending opening the valve completely then closing it a quarter or half turn.

I think this urban legend of the "backing off" of the valve is in the same category of turning a SPG away from you when you open the cylinder valve. When was the last time a SPG exploded?

I teach students to hold their SPG in their hand while they fully open their cylinder valve. That way they can immediately check their cylinder pressure.

All SPG's now have blowout plugs and have had them since the late 1970s, there is little or no possibility of blowing the class face off any more.

I have seen many instructors demonstrate turning the valve on while holding the gauge with the face turned away from them. The problem is, they were starring right into the overpressure relief plug on the back of the SPG.

Your are absolutely right, I suppose that plug could injure an eye, but I've never heard of it happening.

 

[aquaregia]

All SPG's now have blowout plugs and have had them since the late 1970s, there is little or no possibility of blowing the class face off any more.

I have an SPG from the late 1970s. How can I check to see if it has a blowout plug?

 

[Thalassamania]

It likely does, look for a black "dimple" shaped piece of rubber in the back of the gauge, under the boot, if there is one.

 

[FritzCat66]

I am not a big fan of air intergrated computers for several reasons but this is one of the major ones, most have a refresh rate that is too slow to catch the swinging in tank pressure like a standard SPG will.

Easy enough to test; my Sherwood Wisdom AI computer dips in response to a breath test on partially closed valve just like a BnG SPG. So, slow response is no reason to totally avoid AI; but it's a good reason to be picky. :support:

 

[The Mighty Thor]

righty tighty .. and lefty is the other one

Lefty loosey, righty tighty.